Alkaline solutions are especially suitable for the purification of hydrocarbon fractions and particularly sour gasolines including cracked gasoline, straight run gasoline or mixtures thereof, naphtha, jet fuel, kerosene, aromatic solvent, stove oil, range oil, burner oil, fuel oil, etc. Other hydrocarbon fractions include lubricating oil, gas oil, etc., as well as normally gaseous fractions. In addition, other organic fractions containing acidic impurities which may be treated in this manner include, for example, alcohols, ketones, aldehydes, etc.
After the hydrocarbon or other organic fraction has been contacted with the alkaline reagent and the acidic components reacted with and/or absorbed in the alkaline reagent, the purified fraction is separated from the alkaline solution. The alkaline solution then is sent for regeneration in order to remove the acidic components and to restore the activity of the alkaline reagent for further use in the process.
In the prior art a number of patents teach regeneration of aqueous alkaline waste waters by electrochemical means. U.S. Pat. No. 3,801,698 teaches a process for regenerating an aqueous alkali metal sulfate solution in an electrolytic process whereby aqueous sulfuric acid or an aqueous mixture of sulfuric acid and alkali metal sulfate is collected at the anode and is recycled, and aqueous alkali metal hydroxide which forms at the cathode is recycled. Separation of the hydrocarbon phase occurs by settling from the alkali metal hydroxide aqueous solution. U.S. Pat. No. 3,806,435 teaches a process for treating waste liquor containing one or more sulfidic contaminants by an electrolytic treatment using an anode of iron/aluminum or zinc/aluminum and a cathode of iron or zinc, thereby eliminating the sulfidic contamination by forming iron or zinc sulfide which is thereupon precipitated with Al(OH).sub.2 formed by decomposition of the composite anode. U.S. Pat. No. 4,041,129 teaches a process for reducing carbon dioxide and/or hydrogen sulfide levels in a hydrocarbon gas. The process consists of passing the gas through an aqueous sodium hydroxide solution, reacting the effluent liquid with sulfuric acid, stripping the acidic gases therefrom and subjecting the resulting aqueous sodium sulfate solution to electrolysis to regenerate sodium hydroxide and sulfuric acid. The cell used can be a three-compartment cell having an ion-exchange membrane selectively permeable to cations defining the cation compartment and a spaced acid-resistant hydraulically permeable diaphragm defining the anode chamber. The salt solution is passed into the center compartment. Deionized water is passed into the cathode compartment. Migration of the cations into the cathode compartment yields the corresponding metal hydroxide with hydroxyl ions produced by electrolysis of water. Anions in the anode compartment combine with hydrogen ions produced by electrolysis of water to produce the corresponding acid. U.S. Pat. No. 4,246,079 teaches a process wherein sulfur compounds are removed from a hydrocarbon stream by contacting the stream with caustic to partially remove the sulfur compounds, then carbonating the spent caustic solution and passing the carbonate salt solution into an electrolytic cell to convert the alkali metal salt to the alkali metal hydroxide.
However, processes taught in the prior art have several inherent disadvantages. Among the products of the process of U.S. Pat. No. 3,801,698 are sodium sulfate, carbon dioxide and sulfur. The process requires extensive process equipment and the products are not all immediately usable. The process of U.S. Pat. No. 3,806,435 produces iron or zinc sulfide which is precipitated with aluminum hydroxide obtained by decomposition of the anode. Constant replacement of the anode is accordingly required. The process of U.S. Pat. No. 4,246,079 requires that the concentration of sulfuric acid be closely monitored and a substantial portion of the process equipment may have to be constructed of stainless steel to reduce corrosion. The products of the process of U.S. Pat. No. 4,246,079 are not immediately reusable, such as sulfur, without further processing.
The instant invention is directed to a process wherein the products are directly reusable in a refinery operation and which has only a minimal effect on plant wastewater facilities. The process results in relatively high purity alkali metal hydroxide, sulfuric acid and hydrogen.